Strange Sounds Your AC Unit Can Make & What They May Mean


Few things ruin a beautiful summer day more quickly than ominous noises coming from your air conditioning unit. One of the worst things you can do when you encounter an unexpected noise coming from your HVAC unit is to let the system keep running while you try to ignore the noise. While the causes of some noises are fairly innocuous and won't result in much more than increased wear and tear on affected internal parts and on your nerves, others indicate serous issues that may even present a danger to yourself and other household residents.

The following are several common causes of strange AC noises and what you should do if you should hear them. 

Compressor Conundrums 

Banging, clanking, bubbling, hissing, and buzzing are all noises that you might hear coming from an air compressor in distress. These can mean anything from minor fixes to serious compressor conundrums requiring the attention of a professional air conditioning repair service and everything in between. A general rule of thumb concerning malfunctioning air compressors is that the most alarming noises are generally the easiest ones to fix. Loud banging and clanking sounds are often caused by loose pistons, rods, or other internal parts of the compressor and can usually be stopped simply by tightening the offending part. 

However, quieter hissing sounds may have more insidious origins, so don't ignore them even if they aren't nearly as loud as banging noises. Hissing often means that something's leaking, such as usually refrigerant. No leak in history has ever fixed itself, so call a professional if you suspect that your compressor has a leak.

Here's a quick look at other sounds and what they suggest: 

  • If you hear a rattling noise coming from your compressor, the culprit may be the relay control switch.
  • Buzzing sounds may be the result of a variety of conditions, including loose wiring, faulty connections, or an overloaded fan relay switch.
  • If you hear a high-pitched hissing that can adequately be described as a screaming sound, shut the unit off immediately and do not use it again until it has been throughly checked out, repaired, and given a clean bill of healthy by a qualified technician. 
  • ​A humming sound immediately upon starting up the unit may be an indication that something is remiss with the motor. 

Because opening compressors involves the risk of electric shock or other types of injury, always depend on the services of an experienced air conditioner technician rather than trying to tackle the project yourself. 

Belts Gone Bad

If you've ever experienced a loose or otherwise malfunctioning fan belt on your automobile, you know exactly what a bad belt sounds like. Although this isn't a dangerous condition, the sound is highly annoying, and it won't get any better, so call a technician ASAP. If the belt breaks completely, the blower will not longer function. Fortunately, this isn't an expensive or difficult fix; the technician should be in an out of your home within a half an hour at the most. 

Blower Blades Thwapping 

If you ever put a playing card between the spokes of your bicycle and then rode it or was in close proximity to someone who did, you're undoubtedly familiar with the sound of thwapping. If your air conditioning unit starts to thaw, the primary cause is probably a foreign object stuck in the blower blades. After turning the unit completely off and letting the motor cool down, careful check the blower blades for anything that could be causing it to thwap.

If you can't find the cause, call an air conditioning repair service; it's possible that the problem is occurring in the housing of the motor itself, which will require professional expertise in order to properly repair. Learn more about what's wrong with your HVAC unit by visiting resources like


16 January 2017

Streamline Your HVAC System

As a DIY enthusiast, I started doing everything I could to make my household appliances more effective then ever before. I insulated my attic, worked on cleaning the vents around my kitchen appliances, and eventually turned my attention to my air conditioner and furnace. Unfortunately, the process of taking care of my HVAC system was more intense than I had originally anticipated. I realized that I needed to read about air conditioners and furnaces before I started tinkering around. I made this blog to showcase all kinds of different articles that talk about HVAC, so that you can become a more informed homeowner.